390 



Dr. A. D. Waller. 



[Mar. 17, 



General Remarks concerning the Preceding Table. 



The table comprises groups of observations. Nos. I to XI were taken with 

 skins sent to me by Mr. Plimmer from the operating theatre and the post-mortem 

 room of St. Mary's Hospital. Nos. XII to XYIII were taken with, for the most 

 part, an amputation skin sent to me from Guy's Hospital and from Great Ormond 

 Street by the kind directions of Mr. Lane. 



The data of both groups are in complete agreement with the statements made 

 in the text, and with the representative experiment of which the graphic record 

 is reproduced in fig. 1, viz., to both directions of single induction shocks, and to 

 both pairs of directions of alternating tetanising currents the electrical response 

 •of living skin was outgoing ( + ). 



A maximal value of the response under favourable conditions was + '04 to 

 + -05 volt. 



It was noticed on more than one occasion that the summated effect of tetanisa- 

 tion was of about equal voltage to the single response, to a single induction shock 

 ten times as strong. 



It was noticed more than once that the electrical response was small immediately 

 ■after excision, greater 24 hours later, and subsequently diminishing day by day. I 

 consider it probable that the smallness of the response of quite freshly excised 

 skin is an effect of the excitation or " shock" of manipulation. In one particular 

 instance, in which the skin had been very thoroughly cleared of subcutaneous tissue, 

 I observed little or no response on the 1st day, and a typical response on the 2nd 

 and succeeding days. 



Skin No. 2 observation was most carefully followed out. It was undoubtedly 

 living on the 7th day, when the following record was obtained, which illustrates 



i , i : I 



mm. to EO 



Pig. 5 (4213). — Skin No. 2. Close to nipple. 7th day after excision. Positive 

 (outgoing) responses to + and — break induction currents (coil at 10,000), 

 and to brief tetanisation in both pairs of directions (coil at 1000). 



at the same time the fact mentioned above, viz., that the summated effects at a 

 given strength of excitation are approximately equal to the single effects at ten 

 times that strength. 



The same skin afforded data that illustrate the progressively declining " vitality " 

 of surviving skin. The following tabular summary of notes will suffice to illustrate 

 this point : — 



